Core for casting amplifying horns



Aug. 28, 1928..

F. W. TEMPLE CORE FOR CASTING AMPLIFYING HORNS Filed June 1925 0 9 .fl f V WWW/W 3 6 k Z w flfl A mm 0 J, .7 j h v MK [I15 m w 6 2 LULinass;

FEED W. TEMPLE, 0F GIUERO, ILLINOIS, ASSIGNOE OF ONE-HALF TO \VILLIAIMI P. CROTT, OF CHICAGO, ILLINOIS, AND ONE-FOURTH T6 ALFRED IVIABCEEV, 0F

CIGERO, ILLINOIS.

COR-E FUR CASTING AMPLEYING- HORN S.

Application filed June 1,

The invention relates to horns, and particularly to amplifying horns used in connection with loud speaker unitsfor reception by radio.

The horn may also be used in connection with phonographs, and other sound reproducing devices in association with which a horn is desired, for amplification of the sounds reproduced thereby.

One of the principal objects ofthe invention is to obtain, provide a passage for, and amplify the sounds emanating from the loud speaker unit in an amplifying radio horn, which is constructed in a compact form without loss of any sounds reproduced in the horn.

It is another object of the invention to construct the horn in such a manner that the air column passageway is curved and bent on itself in the same plane for a portion of its length, and that, at this portion, a single wall of material forms the walls between the two portions of the single air column passage of the horn.

Another object of the invention is to construct an amplifying radio horn which shall embody a curved air column passageway in a single plane, which may have the form of a bent exponential curve, or substantially a bent exponential curve, although it is not required that the air column passageway should have the form of an exponential curve, since it may have various lengths and various dimensions for the throatarea and the bell opening. I

An additional ob ect of the invention is to construct-the radio amplifying horn of a plastic material, in a single mold or casting, preferably of plaster of Paris, which is a so-called dead material, having a nonresonant property that makes it a good acoustical material, and from which a body with walls is formed of sufficient mass and rigidity to overcome excessive and undesirable vibrations from the diaphragm of the loud speaker and the horn body itself, and the walls of the body may therefore be made smooth and without air cells, permitting the free and unobstructed passage of the advancing sound wave emanating from the loud speaker unit, and which lastic material, in addition, permits of orming the exterior in any desired shape while retaining the air column passageway of a certain 1925. Serial No. 33,937.

dimension, of forming ornaments in relief, and other decorative plastic effects, and which also permits of varied. tinting or coloring.

It is a further object of the invention to construct the horn in such a manner that the bell portion is supported directly on, and is formed directly with the base portion, and therefore does not require extra strength in the goose neck to support the heavy part of the horn.

A further object of the invention isto employ a flexible core, preferably of sponge rubber, for use in the mold, in forming the curved air column passageway.

An additional object of the invention is to construct the amplifying radio horn of inexpensive plastic material and in a closely compacted form by simple molding means to effect saving of time, material, and space,

and yet enable the horn to have excellent.

acoustical qualities and to be efiective for its main purpose of amplifying sounds, to be decorative, and toibe less liable to breakage than if it were not of so compact a form.

The invention willbe explained and more readily understood when read in conjunction with the accompanying drawings, it being understood however that modifications thereof may be made-without departing from the spirit of the appended claims'forming a part hereof.

In the drawings:

Figure 1 is a side elevational view of the amplifying radio horn embodying the i invention.

Figure 2 is a longitudinal cross-sectional view of the horn in the molding forms, in position when being molded, and showing a flexible core for a portion of the air column passageway of the horn, which flexible core portion is keyed to an inflexible core portion.

Figure 3 is a sectional view of the base of the horn showing the loud speaker unit held in place in the nipple, or bushing, secured at the end of the air column passageway and in the base.

Figure 4 is a side elevational view of a core for the air column passageway which is entirely flexible.

The amplifying radio horn of the invention is formed of plastic material, prefer compositions of matter may be used.

manufacture and good decorative possibilities, although clay or other materialsTpr 1 1e molding box, of which one-half is shown at 1 in Figure 2, is set up. Molding block 2 is placed in the bottom of the box 1. It is adapted to have joined to its annular core extension 3 the annular flexible core 4, formed preferably of sponge rubber. The block 2 with its core extension 3, formed of plaster of Paris, is provided with the handle opening 5. In the opening 5, and with its opposite ends firmly embedded and secured in the block 2 and the core extension 3, is the handle bar 6. The annular core extension 3 is provided at its inner end and on its inner annular surface with one or more securing members to hold the inner flexible sponge rubber core 4 to the outer inflexible or rigid core extension 3. Two se curing members or keys 7 and 8 are shown. These are integral with the core extension 3. They are preferably square tapered and are securely glued, or otherwise suitably fastened, to the sponge rubber'core 4.

Molding block 9 is placed in the molding box 1 and molding block 10 is also placed in molding box 1. Molding block 9 fits in position with molding block 2, with its core extension 3 and the flexible core 4, but leaving the space 11 between the blocks, which space is later to be filled with the plastic material to form the amplifying horn 12. Molding block 10, which, with molding block 9, is used in forming the base 13 of the horn, is fitted into place in the molding block 9.

The molding block 10 is provided with an annular core extension 14 which is tapered in form and serves to provide an open space 15 in the base of the finished amplifying horn. The annular core 1portion 14 is provided with a core piece or ey 16 secured and embedded in the inner face of the core 14. The core piece 16 protrudes a slight distance beyond the inner face of the core 14. A nipple 17 is secured in the inner face of the annular core extension 14 and extends outwardly therefrom. The end of the small end portion 18 of the flexible sponge rubber core 4 is brought into the nipple 17 and abuts against the protruding end of the key 16 at 19 within the nipple 17.

The molding block 9 is provided with the eore'piece 20, which serves to form the opening or passage 21 for the wires 22 which connect the radio instrument, (not shown), with the loud speaker unit 23, to be fitted into the nipple 17 and the space 15 in the base of the amplifying horn. The molding block 9 is also provided with an opening 24 poured into the space 11 to form the amplifying horn 12 with its base portion 13 and its annular bell end 25.

v A molding block similar to molding block 9, and which is placed into the other half of the molding box corresponding with the molding box 1, is used in making the amplifying horn. The molding block corresponding to the molding block 9 in the box corresponding to the box marked 1, is not shown, but it will be understood that when the two molding blocks like the molding block 9, with the associated molding blocks 2 and 10, with their inwardly pro jecting core portions 3 and 14, respectively,

and the flexible core 4, with its diminished end 18, are brought together ready for the pouring of the plastic material, they leave the space 11. Prior to assembling the corresponding portion of the molding blocks and boxes the molding blocks are well greased, so that after the molding operation the various parts will not stick together but may be readily removed fronreach other.

After the molding blocks have been thoroughly greased they are firmly fastened together with ropes or clamps and a mixture of molding plaster, dextrine water and suitable coloring materials is poured through the openin 24 into the space 11. a The mixture then orms the amplifying radio born 12 with its base portion 13 and its bell portion 25.

After the mixture has properly set the molding blocks may be removed. Molding block 2, with its inwardly extending core 3, is pulled out by grasping the handlev 6, and with it flexible core 4 is removed. The core 3 and the flexible core 4, secured to the tapered keys 7 and 8, are pulled out of the air column passageway 26, which has been formed by the molding. operation. The nipple 17 for the reception of the loud speaker unit 23 will remain in the casting. The plaster piece 27 in the pouring hole 24, and any other fins or loose plaster, will be out off, and after the casting is dried thoroughly it may be finished and tinted in any desired manner, It is then ready for the reception in the nipple 17 and the space 15 of the loud speaker unit 23 and the conductor wires 22, andfor the use as a radio amplifying horn.

The nipple 17 may be provided'with any suitable means for securing the same in the casting. The nipple shown in Figure 3 is provided with angular extensions 28 and 29, which hold the nipple 17 securely in place.

The flexible sponge rubber core 4, with its end 18, is normally of the contour and configuration shown in Figure 2, and is annular in cross-section throughout. The sponge rubber core stretches into more or less of a straight core when it is being pulled through which the plastic material is to be out, but after it is out of the casting it resumes its normal curved condition, and is ready for the next molding operation.

The curve of the spong rubber core, and the core extension to which it is secured, as

shape and contour, as shown.

well as the curve of the air column passageway, may be an exponential curve. The exponential curve in radio amplifying horns gives very good results, but T do not wish to be limited to the use of any particular form of curve in constructing my amplifying horn.

The air column passageway formed in the casting of the horn by the curved cores 3 and l is in a single plane, and is in such a form that a single wall of material 30 lies between the outer large opening, or mouth of the horn, and the inner small opening, or throat of the horn. By means of this special construction I am able to have one wall serve as the wall for two portions of the single passage. Since the material of the wall is of plaster of Paris, or other material withoutair cells, sounds passing through either portion of the passage are not disturbed or distorted by sounds passing through the other portion of the passage, but there is effected and secured by my construction a great saving in room and space taken by the horn, also a great saving in material in manufacturing the horn, and great strength and rigidity in the completed horn. These savings are eifected and secured without loss of the desirable qualities of the music or voice in the air column passage from the loud speaker unit to the atmosphere.

lln the modified form of core for the air column passageway of the amplifying horn as shown in Figure 4, sponge rubber is used for the entire core. It is not a composite core, as shown in Figure 2. The normal sponge rubber core of Figure Jr-retains its lVhen it is pulled out of the air column passageway in the casting, it stretches and becomes straight, and when it is removed it resumes the nor mal shape, as shown in Figure 4.

The bell end, or the large end, of the modified form of flexible core is made large enough so that it may be readily grasped when it is being ulled out of the air column passageway of .t e horn.

The molding blocks referred to may be shellacked or treated with linseed oil, or the molding blocks may be made by providing inside faces thereof with a coating of gelatine, preferably to the thickness of about an inch.

\Vhat I claim and desire to secure by Letters Patent is:

l. A core for use in casting an amplifywhich i flexible and composed of sponge rubber. I

2. A core for use in casting an amplifying horn for a loud speaker reprotlucer. which is composed of sponge rubber, which is normally bent upon itself in a single plane.

3. A core for use in casting an amplifying horn for a loud speaker reproducer, which is flexible, and composed of sponge rubber, which is normally bent upon itself and in a single plane, which is of a constantly diminishing dimension from its outer bell end to its inner throat end.

4. A core for use in manufacturing ampli' fying horns for loud speaker reproducers made in part of flexible material. and in partof inflexible material, each of said parts having means whereby they may be cooperatively secured to each other, and means in the inflexible portion whereby both portions of the core may be simultaneously removed from the casting.

5. A core for use in manufacturing amplifying horns for loud speaker reproducers made in part of flexible material, and in part of inflexible material, each of said parts having means whereby they may be coopertively secured toeach other, and means in the inflexible portion whereby both portions of the core may be simultaneously removed from the casting, said last-mentioned means comprising a handle bar with its ends embedded in said inflexible portion.

6. A core for use in casting an amplifying horn for a loud speaker reproducer, which is flexible, and composed. of sponge rubber, which is normally bent upon itself and in a single plane, which is of a diminishing dimension from its outer bell end to its inner throat end.

7. A core for use in casting an'amplifying horn for a loud speaker re roducer which is flexible and composed o sponge rubber, which is normally bent upon itself and in a single plane, which is of a diminishing dimension from its outer bell end to its inner throat end.

8. A core for use in casting an amplifying 

